Apelin serum levels in non-diabetic ankylosing spondylitis patients undergoing TNF-α antagonist therapy.

Objectives: To determine whether disease activity, systemic inflammation and metabolic syndrome are potential determinants of circulating apelin in ankylosing spondylitis (AS) patients undergoing TNF-α antagonist-infliximab therapy.

Methods: We investigated apelin serum concentrations in a series of 30 non-diabetic AS patients without history of cardiovascular (CV) events that were treated with the TNF-α antagonist infliximab, immediately prior to an infliximab infusion. Correlations of apelin serum levels with disease activity, systemic inflammation and metabolic syndrome were assessed. Also, potential changes in apelin concentration following an infusion of the anti-TNF-α monoclonal antibody-infliximab were analysed.

Results: No significant correlation between apelin concentration and demographic features, inflammation, adiposity and metabolic syndrome features was seen. Neither differences were seen in basal apelin in different categorical variables associated to AS. Following infliximab infusion, a reduction of apelin serum levels was observed. In this regard, the median (interquartile range) values of apelin decreased from 0.99 (0.74-1.25) ng/ml immediately prior to infliximab infusion to 0.92 (0.72-1.39) ng/ml at the end of the infusion (time 120 minutes). However, the reduction in apelin serum levels following administration of the drug did not achieve statistical significance.

Conclusions: The present study shows that in non-diabetic patients with AS on treatment with infliximab apelin serum levels do not correlate with disease activity or metabolic syndrome. A single infusion of infliximab does not yield a significant change of apelin serum levels in AS patients.